Right now there's no other way to detect something without those markers :) But the marker-thing is a nice idea and with those you can make some cool things too. Maybe they will find another solution for that issue.

These replies are awesome. That's pretty sick. It sure looks better then my current digital interactive table. More technology that goes nowhere. If I put my dick on the table, would it display? Holy-shit thats big. Or would it show me some porn. hmmm .... come to think about it, that would be freaken awesome. The software is kinda ugly though, and jumps around a lot. thank you for posting and sharing it.